Feature: new method addMatrixConsIndicator (#1024)

* ENH: new method `addMatrixConsIndicator`

similar to `addConsIndicator` but for matrix

* Update CHANGELOG.md

* Update test_matrix_variable.py

* use pyscipopt code and doc style

Condensed the addMatrixConsIndicator method signature to a single line and updated the docstring for improved clarity and consistency. Parameter descriptions were streamlined and default values were explicitly stated.

* use pyscipopt code and doc style

* Add return type to add_matrix_constraint method

Specified the return type of the Model.add_matrix_constraint method as MatrixConstraint to improve type clarity and support better static analysis.

* Apply suggestions from code review

Co-authored-by: João Dionísio <[email protected]>

---------

Co-authored-by: João Dionísio <[email protected]>

Author: Zeroto521

CHANGELOG.md

@@ -6,6 +6,7 @@
 - Added support for knapsack constraints
 - Added isPositive(), isNegative(), isFeasLE(), isFeasLT(), isFeasGE(), isFeasGT(), isHugeValue(), and tests
 - Added SCIP_LOCKTYPE, addVarLocksType(), getNLocksDown(), getNLocksUp(), getNLocksDownType(), getNLocksUpType(), and tests
+- Added addMatrixConsIndicator(), and tests
 ### Fixed
 - Raised an error when an expression is used when a variable is required
 ### Changed

src/pyscipopt/scip.pxi

@@ -6809,6 +6809,169 @@ cdef class Model:
 
         return pyCons
 
+
+    def addMatrixConsIndicator(self, cons: MatrixExprCons, binvar: Union[Variable, MatrixVariable] = None,
+                               activeone: Union[bool, np.ndarray] = True, name: Union[str, np.ndarray] = "",
+                               initial: Union[bool, np.ndarray] = True, separate: Union[bool, np.ndarray] = True,
+                               enforce: Union[bool, np.ndarray] = True, check: Union[bool, np.ndarray] = True,
+                               propagate: Union[bool, np.ndarray] = True, local: Union[bool, np.ndarray] = False,
+                               dynamic: Union[bool, np.ndarray] = False, removable: Union[bool, np.ndarray] = False,
+                               stickingatnode: Union[bool, np.ndarray] = False) -> MatrixConstraint:
+        """Add an indicator matrix constraint for the linear inequality `cons`.
+
+        The `binvar` argument models the redundancy of the linear constraint. A solution
+        for which `binvar` is 1 must satisfy the constraint.
+
+        Parameters
+        ----------
+        cons : MatrixExprCons
+            a linear inequality of the form "<=".
+        binvar : Variable or MatrixVariable, optional
+            binary indicator variable / matrix variable, or None if it should be created. (Default value = None)
+        activeone : bool or np.ndarray, optional
+            the matrix constraint should be active if binvar is 1 (0 if activeone = False).
+        name : str or np.ndarray, optional
+            name of the matrix constraint.  (Default value = "")
+        initial : bool or np.ndarray, optional
+            should the LP relaxation of matrix constraint be in the initial LP?  (Default value = True)
+        separate : bool or np.ndarray, optional
+            should the matrix constraint be separated during LP processing?  (Default value = True)
+        enforce : bool or np.ndarray, optional
+            should the matrix constraint be enforced during node processing?  (Default value = True)
+        check : bool or np.ndarray, optional
+            should the matrix constraint be checked for feasibility?  (Default value = True)
+        propagate : bool or np.ndarray, optional
+            should the matrix constraint be propagated during node processing? (Default value = True)
+        local : bool or np.ndarray, optional
+            is the matrix constraint only valid locally? (Default value = False)
+        dynamic : bool or np.ndarray, optional
+            is the matrix constraint subject to aging? (Default value = False)
+        removable : bool or np.ndarray, optional
+            should the relaxation be removed from the LP due to aging or cleanup? (Default value = False)
+        stickingatnode : bool or np.ndarray, optional
+            should the matrix constraint always be kept at the node where it was added,
+            even if it may be moved to a more global node? (Default value = False)
+
+        Returns
+        -------
+        MatrixConstraint
+            The newly created Indicator MatrixConstraint object.
+        """
+
+        assert isinstance(cons, MatrixExprCons), (
+            f"given constraint is not MatrixExprCons but {cons.__class__.__name__}"
+        )
+
+        shape = cons.shape
+
+        if isinstance(binvar, MatrixVariable):
+            assert binvar.shape == shape
+        if isinstance(activeone, np.ndarray):
+            assert activeone.shape == shape
+        if isinstance(name, np.ndarray):
+            assert name.shape == shape
+        if isinstance(initial, np.ndarray):
+            assert initial.shape == shape
+        if isinstance(separate, np.ndarray):
+            assert separate.shape == shape
+        if isinstance(enforce, np.ndarray):
+            assert enforce.shape == shape
+        if isinstance(check, np.ndarray):
+            assert check.shape == shape
+        if isinstance(propagate, np.ndarray):
+            assert propagate.shape == shape
+        if isinstance(local, np.ndarray):
+            assert local.shape == shape
+        if isinstance(dynamic, np.ndarray):
+            assert dynamic.shape == shape
+        if isinstance(removable, np.ndarray):
+            assert removable.shape == shape
+        if isinstance(stickingatnode, np.ndarray):
+            assert stickingatnode.shape == shape
+
+        if not isinstance(binvar, MatrixVariable):
+            matrix_binvar = np.full(shape, binvar, dtype=Variable)
+        else:
+            matrix_binvar = binvar
+
+        if not isinstance(activeone, np.ndarray):
+            matrix_activeone = np.full(shape, activeone, dtype=bool)
+        else:
+            matrix_activeone = activeone
+
+        if isinstance(name, str):
+            matrix_names = np.full(shape, name, dtype=object)
+            if name != "":
+                for idx in np.ndindex(shape):
+                    matrix_names[idx] = f"{name}_{'_'.join(map(str, idx))}"
+        else:
+            matrix_names = name
+
+        if not isinstance(initial, np.ndarray):
+            matrix_initial = np.full(shape, initial, dtype=bool)
+        else:
+            matrix_initial = initial
+
+        if not isinstance(enforce, np.ndarray):
+            matrix_enforce = np.full(shape, enforce, dtype=bool)
+        else:
+            matrix_enforce = enforce
+
+        if not isinstance(separate, np.ndarray):
+            matrix_separate = np.full(shape, separate, dtype=bool)
+        else:
+            matrix_separate = separate
+
+        if not isinstance(check, np.ndarray):
+            matrix_check = np.full(shape, check, dtype=bool)
+        else:
+            matrix_check = check
+
+        if not isinstance(propagate, np.ndarray):
+            matrix_propagate = np.full(shape, propagate, dtype=bool)
+        else:
+            matrix_propagate = propagate
+
+        if not isinstance(local, np.ndarray):
+            matrix_local = np.full(shape, local, dtype=bool)
+        else:
+            matrix_local = local
+
+        if not isinstance(dynamic, np.ndarray):
+            matrix_dynamic = np.full(shape, dynamic, dtype=bool)
+        else:
+            matrix_dynamic = dynamic
+
+        if not isinstance(removable, np.ndarray):
+            matrix_removable = np.full(shape, removable, dtype=bool)
+        else:
+            matrix_removable = removable
+
+        if not isinstance(stickingatnode, np.ndarray):
+            matrix_stickingatnode = np.full(shape, stickingatnode, dtype=bool)
+        else:
+            matrix_stickingatnode = stickingatnode
+
+        matrix_cons = np.empty(shape, dtype=object)
+        for idx in np.ndindex(shape):
+            matrix_cons[idx] = self.addConsIndicator(
+                cons[idx],
+                binvar=matrix_binvar[idx],
+                activeone=matrix_activeone[idx],
+                name=matrix_names[idx],
+                initial=matrix_initial[idx],
+                separate=matrix_separate[idx],
+                enforce=matrix_enforce[idx],
+                check=matrix_check[idx],
+                propagate=matrix_propagate[idx],
+                local=matrix_local[idx],
+                dynamic=matrix_dynamic[idx],
+                removable=matrix_removable[idx],
+                stickingatnode=matrix_stickingatnode[idx],
+            )
+
+        return matrix_cons.view(MatrixConstraint)
+
     def getLinearConsIndicator(self, Constraint cons):
         """
         Get the linear constraint corresponding to the indicator constraint.

tests/test_matrix_variable.py

@@ -336,3 +336,32 @@ def test_performance():
     orig_time = end_orig - start_orig
 
     assert m.isGT(orig_time, matrix_time)
+
+
+def test_matrix_cons_indicator():
+    m = Model()
+    x = m.addMatrixVar((2, 3), vtype="I", ub=10)
+    y = m.addMatrixVar(x.shape, vtype="I", ub=10)
+    is_equal = m.addMatrixVar((1, 2), vtype="B")
+
+    # shape of cons is not equal to shape of is_equal
+    with pytest.raises(Exception):
+        m.addMatrixConsIndicator(x >= y, is_equal)
+
+    for i in range(2):
+        m.addMatrixConsIndicator(x[i] >= y[i], is_equal[0, i])
+        m.addMatrixConsIndicator(x[i] <= y[i], is_equal[0, i])
+
+        m.addMatrixConsIndicator(x[i] >= 5, is_equal[0, i])
+        m.addMatrixConsIndicator(y[i] <= 5, is_equal[0, i])
+
+    for i in range(3):
+        m.addMatrixConsIndicator(x[:, i] >= y[:, i], is_equal[0])
+        m.addMatrixConsIndicator(x[:, i] <= y[:, i], is_equal[0])
+
+    m.setObjective(is_equal.sum(), "maximize")
+    m.optimize()
+
+    assert m.getVal(is_equal).sum() == 2
+    assert (m.getVal(x) == m.getVal(y)).all().all()
+    assert (m.getVal(x) == np.array([[5, 5, 5], [5, 5, 5]])).all().all()